1. Field of the Invention
This invention relates generally to a device for actuating movable cams in a flat knitting machine and, more particularly, to a device for actuating movable cams in a flat knitting machine of the kind having a cam plate and several cams arranged thereon, which cams are movable in a direction substantially perpendicular to a plane of movement of the cam box.
2. Description of the Background
Flat knitting machines are known that have a cam plate and several cams arranged thereon, which cams are movable in a direction perpendicular to the plane of movement of the cam box. The cams are also movable perpendicularly to each of a number of grooves that are formed in a carrier and that cooperate with an engaging element, which run along such grooves. Each engaging element is mounted on a rod that is firmly attached to the respective cam involved, and the carrier is attached to a control shaft that is reversibly driven through predetermined angles.
There are various actuating approaches already known for this kind of flat knitting machine and such actuating procedures are generally divided into the use of mechanical actuating means on the one hand and electro-mechanical actuating means on the other. In both cases, however, the cams of the cam box used for such actuation purposes are generally movable perpendicularly to the plane of movement of the needles in flat knitting machines.
In the case of a purely mechanical device used to actuate the cams, the movement of the movable cams is brought about by fixed studs arranged at the machine end that operate upon the stroke reversal of the carriage, as it moves back and forth. In this fashion, the cams involved assume their desired positions by means of curved guides, which require expensive intermediate elements and other costly mechanical parts.
In the case of electromechanical devices used for the actuating of cams, a distinction must be made between those which use electromagnetic correcting elements and those that make use of stepping motors and the like. Furthermore, it should be noted that electromechanical solutions present a further advantage in that they are particularly applicable for flat knitting machines of the kind that have a variable carriage stroke.
In a system disclosed in German Patent Publication DE-OS No. 2,111,789, a separate electromagnet is installed for each movable cam. The electromagnet is arranged so that no forces result in the stroke direction of the electromagnet, in order to prevent the occurrence of unwanted disturbances to the knitting operation during operation of the machine.
Another solution to the movable cams problem is disclosed in German Patent Publication DE-OS No. 2,622,347, in which the cams cooperate with a number of disks having cam-contoured grooves. The disks are jointly arranged on a control shaft, which can be rotated into predetermined angular positions by means of a stepping motor. The actuation of the cams is accomplished individually or in groups by rotating the control shaft in a manner that is predetermined by the corresponding camcontoured grooves. This system has a particular disadvantage in that it is not suitable for a large number of movable cams, both because of the mechanical expense due to the number of parts and also to the large physical space that is required by this large number of cams. The space problem is particularly problematic if the cams must lie close together in that knitting machine.